seede



I Aug. 10, 1926. 1,595,967

J. A. SEEDE ELECTRIC FURNACE Fild Feb. 13,; 1925 F3 j l0 gm MW FLg. 4-

' Inventor v John Afie'ede HLS Attbrngy so provement.

' Nthereservoir; 1 V I i I v Patented Aug. 10, 1 926.

UNITED STATES JOHN A. sEEnE, 1 E

- 1,595,967 PATENT OFFICE.

scn NEcTAnY, NEW YORK, AssIcNoE To GENERAL ELECTRIC COMPANY, A coEroE-ATIoN on NEW YoEK.

' m mm FURNACE.

Application filed February 13, 1925. Serial Nd. 9,033.

Myinvention relates to electric furnaces 0f the induction type, and has for its object the provision of a furnace of this type which may be operated on a polyphase electric sup ply source. g I

More particularly my invention relates to electric induction furnaces for melting metals which are provided with a looped channel in which a portionoffthe molten .10 charge 1 forms a closed secondary, and in which circulation of the molten charge is produced by; electromagnetic repulsion between the primary winding and the portion of the charge forming the secondary. Such a furnace is shown,lfor example, ina copending application'of James M. f Weed, i

Serial No; 525,660, filedDecember 29,1921, assigned to the same assignee as this ,in- .vention, of which this inventionis an im- In carrying out my inventionl providea plurality of primary windings which may be connected to a polyphasefelectrical supply source. These primarywindings are 'in $5 ductively related'to a branchedmo-lten sec-- ondary, and are arranged with relation .to the secondary so as to produce a'cir'cula tion of chargebymeans of electromagnetic repulsion. -f- H 4 For a more complete understanding of my invention referenceshouldbe had to the accompanyingcdrawing ,in which Fig. 1 is a vertical section view of an electric induction furnace embodyingmy invention; Fig.

a5 2fis afsect'ion view alongflthe line 22 of Fig;.'1', l ooking inthe direction, of the arrowsjFigL ,3 is are'duced perspective view of the-furnace shown in Figs. land 2 5. while "Fig. l is adiagrainmatic view showing the loiconnections, for the primarywindings Referring to the drawing, I have shown myjinvention infone form as embodying a refractory furnacecrucible which is shaped or moulded to provide'an upper res- 145 ervoir l1 fforthe molten charge 12, and a "lower looped channel 1'3 which communij cateswith tl'iefres'ervoir, at arentral region through a c'entral"portv or duct 14 and at axially remote regions through two ports or & ducts 15 and 16 at the axial extremiti'esi'of the channel. ,vAs shown, the channel 13. is

' cylindrical, or annular in shape, although it may have, variousbtheri suitable shapes, and "forms a'closedf loop entirelyj independent of tially coincident with thejaxis of the chanshown, the'winding 22 has its center spaced The crucible, 10 may be, formed in any suitable manner, for example, by tamping the'plastic material from which the crucible is made around a suitable core. If it is de sired, the crucible may be built up, from preformed parts which are cemented'togethe'r.

At its lowermost portion the channel 13 is divided into two branches 17 and 18 whereby an aperture 19 is provided in the crucible for a central-leg ofa magnet core 20. This core also extends through an aperture '21 provided in the crucible, whichapertureis substantially concentric with the channel 13, and completely e'ncirclesthe two branches 17 and 18 of the channel. p

On the'core 20 are two primary windings 22 and 23. These primary windings are inserted in opposite ends of the aperture 21 in the crucible, and have their axes substannel 13. Theyare positioned axially so that their centers are on opposite sides of the I center of the channel 13," and likewise on opposite sides'of the central port 14. As

.80 somewhat to the left, while the winding 23 has its center spaced somewhat to the right of the center of the channel.

Various connections may be used between the primary windi gs 22 and 28 and the source of supply. When operating on a three-phase source of supply the well known Scottconnection may be used asindicated in Fig. 4; in which one terminal of the winding 22 is connected to "a central tap 210m the otherwinding 23 which is provided with a greaterv number of turns. The remaining terminals "25, 26 and 27- ofthe windings are connected to ajthree-phase source of supply 28. With this connection the currents induced in the respective ends or branches of the molten secondary in the channel 13 are displaced 90 in phase with respect to each other. Wheresuitable two-phase current is available, the primary coils may be connected directly tothe source of supply.

-The refractorycrcuiblejlO is preferably enclosed in a protecting metallic casing 29. A spout 30 is, provided through which the charge may be poured from the reservoir, for example, by tilting it on a suitable support. The top of the reservoir is preferably closed by a cover.31. c o I q i In" its operation the furnace may be started by pouring in a sufficient quantity secondary for the primary windings 22 and 23. Heat is then generated by the induced currents in the closed secondary, any additional charge may be melted by putting itin the reservoir 11. Due to the axial position or the primary windings 22 and 23, electromagnetic repulsive iorces willbe exerted on the molten secondary tending to force it fromeach end of the channel 13 in an axial direction towards the centre. The molten secondary will be pushed toward the right by the winding 22, and toward the left by the winding 23. This results in an increase "pressure in the central portion of the molten charge whereby the charge is forced upward through the "port 14 into the reservoir. The charge is free to return to the channel 13 'from the reservoirthrou'gh the two end ports 15 and 16. It will thus be observed that a circulation of charge will be set up in an axial direction through the secondary channel to the reservoir, and from thcreservoir back to the channel. The charge also has a certain "amount or flow in a' circumferential direction in the channel, partied larl'y in re ions in the vicinit oi the axial center "of the channel. In other words, the molten charge in a central circumferential Zone or the channel has a somewhat circum- "fe'rential direction of flow in passin from regions of high pressure to the region of lower pressure at the port 14 through which the molten charge esca es;

V'hi'le I have described my invention as embodied in concrete form and as o erating in a specific manner in accordance with. the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled the art withoutdeparting from the spirit of my invention, the scope of which is s'et'for'th in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

l An induction furnace comprising a crucible formin a reservoir for the charge and looped channel communicating with said reservoir, and a plurality of, primary windings inductively associated with said channel for inducing heatin currents in a conductive charge in said channel, said'prilnary windings bein so placed with respect to said channel that oppositely directed electromagnetic repulsive forces are exerted by said primary windings respectively on the ortion of the charge in said channelwherey a circulation of molten charge is produced between said reservoir and said channel.

2. An induction furnace coniprising'a refractory crucible forming a reservoir for the charge and a looped channel in which a portion of the charge forms a closed secon-- dary, said channel being connected with said reservoir at a central region and at regions spaced axially from said central region, and a plurality 01 primary windings inductively arranged with respect to said channel so as to produce a circulation of molten charge by electromagnetic repulsion between said reservoir and said channel, said charge pass ing through said central region in one direction and through said axially spaced regions in an opposite direction; a

3. An induction furnace comprising a re= fractory crucible iorining'a reservoir for the charge and a looped channel in which a portion of the charge forms a closed secondary, said channel being connected with said reser voir at a central region of saidseconda-ry and at axially remote regions of said secondary, and a pair or primary windings inductively related to said secondary dislplaced axially from said central region, w iereby electromagnetic repulsive forces are exerted on said secondary producing a circulation of molten charge between said reservoir and said channel having a common path through said central region.

4. An induction furnace comprising a re fractory crucible forming a reservoir for the charge and a looped channel in which a portion of the charge forms a closed secondary, said channel being connected with said reservoir at a central regiomand at two regions axially remote therefrom, and a pair of primary windings inductively arranged 3 to exert repulsive forces on said secondary tending to force the molten metal from the axialextremities or said channel toward said central region whereby the molten charge is caused to circulate between said channel and said reservoir.

5. An induction furnace comprising refractory crucible forming a reservoir for the charge and a looped channel in ivl'iioh a portion of the charge forms a closed secondary, said channel being connected wit-h said reservoir at a central region and at'two axially remote regions, a magnet core interlinkiiig said channel, and a panof primary windings on said core spaced in opposite directions from the center of said channel whereby the molten charge is forced by electromagnetic repulsion out of said channel into the reservoir through said central region, the

charge returning from the reservoir to the channel through said axiallyremote regions.

6. An induction furnace comprising rc- 'fractory crucible forming a reservoir for the charge and an annular channel communicate ing'with said reservo'irthrough acentra'l and two axially remote orts, a magnet core interlinking said channel, and two primar windings on said core situated on op osite sides or said central port 'ivhereby a re ulsive force is exerted tending to force the molten charge axially from the ends of said channel through said central port into said reservoir, the charge returning to said channel through said axially remote ports.

7. A polyphase induction furnace for melting metals comprising a refractory crucible forming a reservoir for the charge and an annular channel in which a portion of the charge forms a closed secondary, said crucible providing a port connecting central regions of said reservoir and said channel and axially remote ports connecting the ends of said secondary with said reservoir, a magnet core interlinking said channel, a pair of primary windings on said core inserted in said channel and a polyphase source of supply for said primary windings, said primary windings being spaced axially of said channel adjacent the ends'thereof so as to exert electromagnetic repulsive forces on saidsecondary and thereby force the molten charge axially from the ends of said channel through said central port into said reservoir,

the charge returning to said channel through said axially remote ports.

8. An induction furnace comprising a crucible forming a reservoir for the charge and a looped channel communicating with said reservoir at central and axially remote regions, said channel being divided into two branches, a magnet core encircling the branches of said channel, a plurality of primary windings on said core for inducing heating currents in a conductive charge in said channel, and a polyphase electric supply source for said windings, said windings being so placed with respect to said channel that oppositely directed electromagnetic repulsive forces are exerted on the portion of the charge in said channel so that a circulation of molten charge is produced between said reservoir and said channel through said central and axially remote regions.

In witness whereof, I- have hereunto set my hand this 12th day of February, 1925.

JOHN A. SEEDE. 

